So, I agree that a request like that regarding some idea X contributes to the silence of those who disagree with X.

That said, if there are a hundred people, and each person is (on average) ten times more likely to devote a unit of effort to talking about why X is wrong than to talking about why X is right even in situations where they are unsure whether X is wrong or right, then without some request along those lines there will effectively never be a discussion of why X is right.

That isn't necessarily a problem; maybe we're OK with never having a discussion of why X is right.

But it does mean that "summary dismissal" isn't a unilateral thing in cases like that. Yes, in such a case, if I make such a request, I am contributing to the silencing of the anti-X side as above... but if I fail to make such a request, I am contributing to the silencing of the pro-X side (though of course I can't be held accountable for it, since the responsibility for that silencing is distributed).

I try to stay aware that the end result sometimes matters more than whether anyone can hold me accountable for it.